public readonly bool Intersects(Box2 box, out float distance, out Vector2 hitPos)
{
hitPos = Vector2.Zero;
distance = 0;
var tmin = 0.0f; // set to -FLT_MAX to get first hit on line
var tmax = float.MaxValue; // set to max distance ray can travel (for segment)
const float epsilon = 1.0E-07f;
// X axis slab
{
if (MathF.Abs(Direction.X) < epsilon)
{
// ray is parallel to this slab, it will never hit unless ray is inside box
if (Position.X < MathF.Min(box.Left, box.Right) || Position.X > MathF.Max(box.Left, box.Right))
{
return(false);
}
}
// calculate intersection t value of ray with near and far plane of slab
var ood = 1.0f / Direction.X;
var t1 = (MathF.Min(box.Left, box.Right) - Position.X) * ood;
var t2 = (MathF.Max(box.Left, box.Right) - Position.X) * ood;
// Make t1 be the intersection with near plane, t2 with far plane
if (t1 > t2)
{
MathHelper.Swap(ref t1, ref t2);
}
// Compute the intersection of slab intersection intervals
tmin = MathF.Max(t1, tmin);
tmax = MathF.Min(t2, tmax); // Is this Min (SE) or Max(Textbook)
// Exit with no collision as soon as slab intersection becomes empty
if (tmin > tmax)
{
return(false);
}
}
// Y axis slab
{
if (MathF.Abs(Direction.Y) < epsilon)
{
// ray is parallel to this slab, it will never hit unless ray is inside box
if (Position.Y < MathF.Min(box.Top, box.Bottom) || Position.Y > MathF.Max(box.Top, box.Bottom))
{
return(false);
}
}
// calculate intersection t value of ray with near and far plane of slab
var ood = 1.0f / Direction.Y;
var t1 = (MathF.Min(box.Top, box.Bottom) - Position.Y) * ood;
var t2 = (MathF.Max(box.Top, box.Bottom) - Position.Y) * ood;
// Make t1 be the intersection with near plane, t2 with far plane
if (t1 > t2)
{
MathHelper.Swap(ref t1, ref t2);
}
// Compute the intersection of slab intersection intervals
tmin = MathF.Max(t1, tmin);
tmax = MathF.Min(t2, tmax); // Is this Min (SE) or Max(Textbook)
// Exit with no collision as soon as slab intersection becomes empty
if (tmin > tmax)
{
return(false);
}
}
// Ray intersects all slabs. Return point and intersection t value
hitPos = Position + Direction * tmin;
distance = tmin;
return(true);
}
public Box2Rotated(Box2 box, Angle rotation)
: this(box, rotation, Vector2.Zero)
{
}
public Box2Rotated(Box2 box, Angle rotation, Vector2 origin)
{
Box = box;
Rotation = rotation;
Origin = origin;
}
public Box2Rotated(Box2 box)
: this(box, 0)
{
}
